The present invention relates to the decoration of injection molded parts, and particularly the decoration of only a portion of an injection molded panel or the like.
Molded or formed plastic articles are often covered with coverstock such as fabrics and/or foams in applications such as automotive interior trim panels, most notably door interiors. Currently, most of these coverings are applied as a secondary operation after the plastic is formed, using adhesives to bond the coverstock to the plastic.
Manufacturers of automotive trim panels are currently developing methods to insert the coverstock in the injection mold; the heat of the plastic injected into the mold results in a bond between the fabric and the molded plastic. Thus no adhesive or labor-intensive secondary operation is required. The resultant part still requires the trimming and wrapping of the fabric around the rigid plastic, however.
U.S. Pat. No. 4,740,417 discloses one known technique for adhering a porous, foam backed fabric to a thermoplastic substrate, by the use of a vacuum mold. U.S. Pat. Nos. 4,781,956 and 4,802,948 disclose a technique for fabricating an interior trim component for motor vehicles, having cushioning effects in pre-selected areas. None of these patents, however, addresses the particular problem solved by the present invention.
Disadvantages of current in-mold decoration methods for this type of application in addition to the continued need for secondary operations includes the fact that many automotive interior trim parts are not totally covered in fabric. Many parts have sections that are covered in fabric, and others which are simply hard plastic ("class A surface"). To manufacture such parts, the decorated areas of the part needed to be molded separately, covered either in-mold or in a secondary operation with the decorative fabric, and then fastened to the other "class A" parts using mechanical fasteners. Aesthetic considerations dictate that the line formed at the visible interface between the class A surface and decorative material (split or separation line), be clean and of uniform width.